1. Field of the Invention
The present invention relates to a reinforcing fiber sheet which can easily be handled at a reinforcement cite where structures, such as bridges or elevated roads, are reinforced using fiber reinforced plastics and which enables the reinforcement strength of the structure to be increased, a method of manufacturing such a reinforcing fiber sheet, and a method of reinforcing structures using the sheet.
2. Description of the Related Art
Reinforcement of bridges and piers of elevated roads using fiber reinforced plastics has been practiced.
Following reinforcing methods have been known:
(1) The method in which a set fiber reinforced plastic is adhered to the portion of a pier to be reinforced. PA1 (2) The method in which a prepreg is adhered to the portion of a pier to be reinforced, a press tape is coated on the prepreg to prevent deformation which occurs during the thermosetting, and then the prepreg is caused to thermoset to make it a fiber reinforced plastic. PA1 (3) The method in which a cloth made of reinforcing fibers is wound around the portion of a pier to be reinforced, the cloth is impregnated with a room-temperature setting type matrix resin, a press tape is coated on the cloth, and then the matrix resin is left to make it a fiber reinforced plastic.
However, the method itemized by (1) cannot be conducted on the curved portion of the pier, although it assures effective reinforcement efficiency.
The method itemized by (2) has a disadvantage in that it requires thermosetting of the prepreg adhered to the portion of the pier to be reinforced at the reinforcement cite.
The cloth employed in the method itemized by (3) is obtained by, for example, plainly or diagonally weaving reinforcing fibers, and is thus characterized in that it is weak at the intersections of warps and wefts. Hence, the cloth cannot assure sufficient reinforcement effect when it is made into a fiber reinforced plastic.
In another reinforcing method, reinforcing filaments impregnated with matrix resin are wound around the portion of the pier to be reinforced by the filament winding process and then thermoset to make it a fiber reinforced plastic at the cite. However, the structures on which this method can be performed are restricted, and expensive equipment is required. Hence, this method is not practical.